Wenner method

Fig. 3-14 Circuit of a measuring instrument for determining the apparent soil resistance by the Wenner method.

The Wenner method is chiefly used to determine the grounding resistance along the pipeline track and the installation positions for cathodic structures. Local limited soil resistivity is most clearly determined from the grounding resistance of an inserted Shephard rod (see Fig. 3-18). Soil stratification can be recognized from the apparent specific soil resistivity, p, by the Wenner method, if a is varied. 

Measurement of resistivity The most usual method of measuring soil resistivity is by the four-electrode Wenner method. Figure 10.48 indicates the basic circuit. The mean resistivity is given by... 

Wenner method. Normally Ct, Cz and Pu Pt are stetl rods, bm for high -accuracy Cu/CuS04 electrodes should he used for Pu Pi... 

This method gives an average in situ resistance at a depth equal to the pin spacing. Foreign buried structures may interfere with the measurements when using the Wenner method. Therefore, it is important to position the pins perpendicular to the underground pipeline [44]. If the pins are positioned parallel to the pipeline, it would result in lower resistance values than the actual resistance. If the specific soil resistance varies vertically... 

Wenner method. Normally Ci, Ci and Pv, Pi are steel rods, but for higher accuracy Cu/CuS04 electrodes should be used for P, Pi... 

Field measurement of soil resistivity using the Wenner four-electrode method... 

Direct shear test of soils under consolidated drained conditions pH of soil for use in corrosion testing Field measurement of soil resistivity using the Wenner four-electrode method Optimum S03 in portland cement... 

New York (1933) 7) R.R. Wenner Thermochemical Calculations , McGraw Hill, New York (1941) 8) J.M. Cork Heat , J. Wiley, New York (1942) 9) J. Reilly W.N. Rae Physicochemical Methods , Van Nostrand, New York (1943) 10) H.S. Carslaw J.C. Jaeger Conduction of Heat in Solids , Clarendon Press, Oxford (1947) 11) M. Jacob, Heat Transfer , J. Wiley Sons, New York, V. 1 (1949) 12) D.Q. Kern Process Heat Transfer , McGraw Hill, New York (1951) 13) F. Reif... 

The present method is that of Wenner 21 and is applicable to other arylacetonitriles.4... 

The methods for the preparation of alloxan have been reviewed earlier.2 3 The present method is essentially that of Wenner.4... 

During application of the method, a current is injected into the ground by a pair of surface electrodes and a resulting potential field is measured between a second pair of surface electrodes. A schematic of such a configuration called a Wenner array, is shown in Figure 8. The subsurface resistivity is calculated from the electrode separation, applied current, and measured voltage. 

Buried pipelines are subject to external corrosion from ground water and highly conductive soils. The corrosiveness of soils is often estimated based on soil resistivity measurement. The measurement is made with the Wenner four-pin method, which is used in conjunction with a Vibroground(1 and a Miller U 10-pin conductor set to determine the average electrical resistivities. A general relationship between corrosion and soil resistivity is as follows ... 

A further example, which confirms the necessity of evaluating the resistivity of the medium very carefully, concerns the corrosion of rebars in reinforced concrete. In this caae the intensity of the current flowing between the anodic and cathodic zones of a macrocell depends on the resistivity of the concrete and the extent of the region involved. To determine the concrete resistivity various methods have been developed, which can be applied in the laboratory [14] as well as in the field [15]. It should be noted, however, that in the latter case most researchers have pursued the approach suggested by Wenner [16] for the evaluation of the resistivity of soils. The contribution of the ohmic drop to the electrode overvoltage cannot be neglected when the values of the corrosion rate of the rebars are appreciable, even if the current intensity is small within a given polarization potential interval, because under such conditions the interpretation of experimental results could be completely distorted. 

Fig. 15.8 Wenner four-pin method for measuring soii resistance.

This method is based on the same principle as the Wenner four-pin test method. There are four points of electrical contact with the soil the current is driven through the two... 

ASTM G 57-95A, Standard Test Method for Field Measurement ofSod Resistivity Using the Wenner Four-Electrode Method, ASTM International, West Conshohocken, PA, 1995. 

ASTM G57 (2001). Field Measurement of Soil Resistivity Using the Wenner Four-electrode Method American Society of Testing and Materials, West Conshohocken, PA. 

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